iPhone/Android: New York City has an official app for its public transportation system, and it's pretty darned thorough. You get standard colored transit maps, detailed neighborhood grids, and all the upcoming departure times for any stop you click on.

The app is basically a fast-loading pinch-and-zoom map stuffed with transit info—fairly up to date, according to one of our Manhattan correspondents. It doesn't appear to do much offline caching at first glance, though, so it's the kind of app you'll want to use when you're above ground, rather than in the tunnels.

NYCmate is a free download for iPhones and Android phones. Android owners can grab it with the QR code at left; another code and the iTunes link are included at the official site, too.